Neuroendocrine tumors of visual system – Merkel cell carcinoma

Introduction
To describe cases of Merkel cell carcinoma. Belonging to the APUD - system tumors, the highly malignant Merkel cell carcinoma affects in 10% the ocular adnexes, 50-60% of the patients develop a metastasis to the lymph nodes, and the five year surival rate is only 38%. 30% of the tumors recur after one year.

Material and methods
In the last eight years the Merkel cell carcinoma was diagnosed in four patients and was treated by wide resection, radiotherapy and cytostatic drugs. Histological and immunohistological examination was performed.

Results
In three cases the carcinoma was diagnosed in the upper lid and in one case in the eyebrow. Two patients could not be cured. Characteristic is clinical uniform appearance of the tumor as painless, reddish nodule with smooth surface, telangiectatic blood vessels, fast growing and fast leading to metastasis. Furthermore, the histological characteristics of the tumor were found as well as NSE, S100 proteins and neuroendocrine granula, which allow to classify to the APUD - system and to distinguish from the more benign tumors.

Conclusions
As neuroendocrine tumor the Merkel cell carcinoma represents a high malignant tumor in ophthalmology. The certain diagnosis is only made by histological and immunohistological examination. A full - thickness resection followed by radiation, should be performed as soon as possible.